Lamp circuit



Patented Aug. 12, 1947 LAMP CIRCUIT Carl E. Atkins, Evanston, and Frank Furedy, Chicago, Ill., assignors, by mesne assignments, to Sun-Kraft, Inc., Chicago, Ill., a corporation of Delaware Application October 24, 1942, Serial N o. 463,256

6 Claims. 1

This invention relates to a circuit for energizing a gaseous discharge lamp by high frequency currents, and more particularly for energizing an ultra-violet, gaseous discharge lamp of the electrodeless type.

I t is an object of this invention to provide a high frequency, energizing circuit for a portable ultra-violet lamp so that the same may -be selectively connected to a source of alternating current or a battery, of relatively low Voltage.

It is a further object of the invention to pro` vide a high frequency, oscillating circuit capable of energization selectively from a relative low voltage, alternating current power supply or battery and yet supply a suflicient amount of high frequency power to energize an electrodeless, ultra-violet lamp for therapeutic or other analogous uses.

Other and further objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying schematic drawing of -a circuit constructed in accordance with the invention.

As shown in the drawing, the lamp 2 may be a quartz, ultra-violet ray lamp, lled with mercury vapor, argon, neon, helium, and krypton or other suitable rare gases, and With fa globule of mercury, after which the lamp is sealed 01T.

High frequency current for the excitation of the lamp is supplied thereto by external clips or terminals 4, which also form means mounting the lamp in its reector.

The oscillating circuit, of which the lamp 2 is a part, compri-ses thermionic tubes 6 and 8 having cathodes I and I2, control grids I4 and I 6, screen grids I8 and 28, and anodes or plates 22 and 24. Each of the cathodes I0 and I2 cornprises dual filaments capable of energization from a low voltage, heater source to supply a large emission. Thus all four filaments are connected in parallel to the supply leads 26 and 28 from a low voltage source of one and one-half voltage rating. An adjustable timer v29 is connected in the lead 26 to deenergize the tubes and the lamp after .a predetermined, adjusted period of treatment. The plates 22 and 24 are connected to the opposite ends 30 and 32 of an oscillator coil 3.4 having a center tap, 36 connected by Wire 3,8 to the positive plate supply lead 40. The center tap 36, the wire 38, and also the positive vsupply lead 48 are grounded to the metal frame of the lamp as at 42 through a condenser 44.

The opposite ends 30 and 32 of the oscillator coil 34 are connected by Wires 46 and 48, respectively, in which are interposed condensers 50 and (C1. A35h-24:4)

2 52, to the terminals 4 of the gaseous discharge tube or lamp 2. y

The negative power supply lead 54 is connect.. ed to the lead 26 fromthe positive side .of the heater supply source. The power supply leads` 40 and 54 are .connected to a source having :a voltage rating of the order of ninety to one hundred and ten volts.

The screen grids I8 and 2.0 are tied together .by a wire 56 .connected to the positive power supply lead 4I) by a Wire 58, in which is interposed a resistor 60. The control grids Maand I6 are connected to the cathodes through grid resistors 62 and 64, respectively, the resistors being preferably connected to the positive sides of the lilaments of the respective tubes. The control grids are also coupled to the oscillator coil 34, the grid I4 .being connected by a Wire 66 to a .cendenser 68, in turn connected to an intermedat. tap 'I8 of the oscillator coil atv a point between the central tap 36 and the end 32 of the coil, while the control grid I6 is connected by a Wire 1;2 to a condenser 14, in turn connected te an intermediate tap 'L6 o f the oscillator coil .at e. point between the center tap 36 and the end 3.0,.

A condenser I8 is connected on one the screen grid lead 58 .and grounded at itsether side to the frame of the lamp as at 8g), A con.- denser 82. is connected on one Side .11.0 .a wire 8.4 which joins the lamentsof the tube .8 to the laments of the tube .6, and on its .otherSl-c `is grounded to the frame as at 8,6. It, will :be evident that through the condenser `=8,2 the p tive side of the heater source and the negative Side 0f the plate supply source is grounded tothe frame vof the lamp.

The lamp 2 forms a part ofthe tuned circuit, of which the oscillator coil 34 also forms. a,'p3'.1t, and it will be evident that va resonance current flows through the lamp to energize the saine. The lamp is isolated from the direct current ccm.-

ponent of the plate voltage by means of the con-v densers 50 and 5,2. The circuit is maintained in balance in respect to the high frequency oscillating current, and parasitic oscillations .which would cause flickering of the tube are suppressed, by the connections .of the condensers 44, 1.8, and 82, as shown in the drawing. These condensers, as well as the condensers 58 and 52, Servet render the lamp unit shockproof.

The supply leads 26 and 28 are connected to blades 88 and 90 of a manual selector switch 92 by which they are connected selectively to contacts 94 and 96 or contacts 98 and |00. Similarly, the leads 54 and 40 are connected to blades de tov |02 and |04 of the switch 92 by which they are connected selectively to contacts |06 and |08 or contacts and H2.

The contacts 94 and 96 are connected to the opposite ends of a low voltage (1 .5 volts) secondary l I 4 of a heater transformer having its primary I I6 connected to the wires ||8 and |20 of a. power supply cord. The contacts 98 and |00 `are connected to the positive and negative sides, respectively, of a battery |28 of 1.5 volts which may be housed in the lamp carrying case (not shown). The contacts |06 and |08 are connected .by wires |22 and |24 to the wires H8 and |20 of the supply cord While the contacts ||0 and ||2 are connected to the negative and positive sides, respectively, of a 90 volt battery |28.

It will be evident that upon operation of the switch 92 to its left position, the laments will be connected across the secondary ||4 while the plate and return leads 40 and 54 will be directly connected through the supply cord to the 110 volt alternating current power supply. Upon movement of the switch 92 to its right position, the filaments will be connected across the 1.5 volt battery while the plate and supply leads are connected across the 90 volt battery.

The switch 92 may have a third, or mid-position, as shown, in which the power leads are disconnected from all sources. y

In a preferred construction the tubes 6 and 8 are 3Q5GT tubes and the circuit constants have the following values:

(1) The resistors 62 and 64I- 10,000 ohms;

(2) The resistor BIJ-2,000 ohms;

(3) The condensers 44, 50, 52, 58, 14, 18 and 82-250 micromicrofarads;

(4) The oscillator or induction coil 34 consists of 16 turns of No. 18 cotton-covered wire on a cylindrical form 1% inches in diameter, and has a winding length of one inch. The taps and 16 are brought out 21A; turns on each side of the center tap 36.

It is obvious that various changes may be made in the specic embodiment of the invention set forth for the purposes of illustration without departing from the spirit of the invention. Accordingly the invention is not to be limited to the specic embodiment shown and described but only as indicated in the following claims.

What we claim is as follows:

1. A circuit for energizing an ultra-violet gaseous discharge la-mp comprising a thermionic tube oscillator` circuit including an induction coil, and a circuit including the gaseous discharge lamp connected across the induction coil and forming with said coil a tuned tank circuit determining the frequency of operation of the oscillator,

2. A circuit for energizing an ultra-violet gaseous discharge lamp, comprising a pair of thermionic tubes having plate, cathode, and grid electrodes, an induction coil having a center tap, a source of electric current connected to said center tap, connections from said coil on opposite sides of said center tap to the plates of said tubes, the cathodes of said tubes being connected to said source, connections from said coil on opposite sides of the center tap to the control grids of said tubes to apply thereto potentials in proper phase to produce oscillating plate current, and a circuit connecting the gaseous discharge lamp to said induction coil on opposite sides of said center tap and providing shunt tuning capacitance for said coil to determine the frequency of said oscillating current. 5 3. A circuit for energizing an ultra-violet, gaseous discharge lamp comprising a push-pull oscillator having a tuned tank circuit including an oscillator coil, and said lamp connected in shunt to said coil and providing shunt tuning capacitance for said coil to determine the frequency of operation of said oscillator.

4. A circuit for energizing an ultra-violet, gaseous discharge lamp comprising a push-pull oscillator having a tuned tank circuit including an oscillator coil having a center tap connected to a source of electric energy and grounded through a capacity and said lamp, said lamp being connected in shunt to said coil and providing shunt tuning capacitance for said coil to determine the frequency of operation of said oscillator.

5. A circuit for energizing an ultraviolet, gaseous discharge lamp comprising a push-pull oscillator having a pair of thermionic tubes, a tank circuit connected to the plates of said tubes and including an oscillator coil to the ends of which the lamp is connected for tuning the coil to ldetermine the frequency of operation of the oscillator, said coil having a center tap forming a positive power supply lead for the plates of said tubes, said tubes having laments, lament supply leads connected to said filaments, a negative platepower supply lead connected to one of said filament leads, and condensers connected on one side to points of equal potential and connected on the other sides to said positive and to said negative supply leads.

6. A self-excited oscillator circuit for energizing an ultra-violet gaseous discharge lamp, comprising a tank circuit determining the frequency of operation of the oscillator and a pair of thermionic tubes connected in push-pull to said tank circuit, said tank circuit including an induction coil in the plate circuits of said tubes, and a circuit in shunt to said coil for tuning the tank cir- 45 cuit and including a pair of coupling condensers in series with said gaseous discharge lamp.

CARL E. ATKINS. FRANK FU'REDY.

REFERENCES CITED The following references are of record in the file of this patent:

OTHER REFERENES F. E. Terman, Radio Engineering, 2d ed., 1937, McGraw-Hill, N. Y. C., page 370. (Copy in Library of Congress.) 

